Mammut americanum (Kerr, 1792)

Davis, Matt, Nye, Benjamin D., Sinatra, Gale M., Swartout, William, Sjӧberg, Molly, Porter, Molly, Nelson, David, Kennedy, Alana A. U., Herrick, Imogen, Weeks, Danaan DeNeve & Lindsey, Emily, 2022, Designing scientifically-grounded paleoart for augmented reality at La Brea Tar Pits, Palaeontologia Electronica (a 9) 25 (1), pp. 1-37 : 26-28

Mammut americanum

( Figure 18 )

Behavior. Our model of an American mastodon ( Figure 18 ) follows typical reconstructions (e.g., Figure 2A ) of Mammut americanum as a stocky elephant-like animal with shaggy brown fur (Witton, 2020). Although this general appearance is well supported by numerous skeletal finds, there is actually little direct evidence that mastodons were covered in hair despite over a century of paleoart that almost exclusively reconstructs them with dense fur (Witton, 2020). There has been only one find of preserved mastodon fur: a skull from Wisconsin with two small patches of hairy skin (Hallin and Gabriel, 1981; Hallin, 1983; 1989). Unfortunately, these patches are described only briefly and have never been figured in the scientific literature beyond an SEM picture of one hair (Hallin, 1989). The patches consisted of hollow guard hairs with a furry undercoat similar to that of aquatic mammals (Hallin, 1983). Hallin and Gabriel (1981, p. 199) concluded that, “This occurrence of mastodon hair supports the accuracy of illustrations which depict mastodons as having been hairy.”, although they interestingly thought the hair pointed to a semiaquatic lifestyle for mastodons instead of cold weather tolerance, the typical reason given for mastodons’ (hypothetical) fur coat (Hallin, 1983).

Are these two patches of hair enough to conclude that mastodons were entirely covered in thick fur? While mastodons, like modern elephants, certainly had some hair, it is unclear if they needed thick coats to keep warm at the northern, interglacial limits of their range in the Arctic and Subarctic (Zazula et al., 2014; Larramendi, 2016). These large-bodied animals certainly would not have needed thick fur in the subtropical climate of Florida where they were also common (Zazula et al., 2014). If the Columbian mammoth was not thought to have extensive fur, it is also unclear why the similarly sized, yet even more compactly proportioned, mastodon needed a thick fur coat. As they cooccurred in Pleistocene Southern California, reconstructions at the Tar Pits often show mammoths and mastodons in the same scene, the former nearly naked and the later thickly furred (e.g., Figure 2B ). Surely mastodons’ mixed or closed habitat

PALAEO- ELECTRONICA.ORG preferences (Haynes and Klimowicz, 2003) were not enough to account for this thermal disparity ( Figure 2B ). Interestingly, there is one piece of paleoart at La Brea Tar Pits that displays a mastodon without thick fur ( Figure 19 ). However, this 1968 life-sized sculpture by Howard Ball is located at the west end of the Lake Pit, an area currently under construction and partially obscured by vegetation with low visitor traffic. It is likely one of the least viewed and reproduced pieces of paleoart onsite.

If the evidence isn’t conclusive for mastodons’ fur, why did we reconstruct them with it? Because brown fur matches most of the previous reconstructions at the Tar Pits Museum, and it visually separates mastodons from mammoths. While the stockier skeleton, straighter tusks, and conical teeth of mastodons are readily visible to the professional paleontologist, the average museum patron often treats mammoths and mastodons as interchangeable (Hallin, 1989). For example, across the street from La Brea Tar Pits, the Los Angeles Metro displays a large banner proudly announcing the discovery of “Hayden”, a juvenile mammoth, while constructing the Wilshire/Fairfax subway station. The reconstruction of Hayden the mammoth they use is a tracing of a mastodon reconstruction previously found on the Museum’s website. A recent PBS documentary filmed at La Brea Tar Pits even showed a stock picture of a woolly mammoth for their mastodon reconstruction. The low poly aesthetic of our mastodon ( Figure 18 ) is ambiguous enough that we feel comfortable publishing it. If we do find more evidence that mastodons had fur, then the model will be accurate. However, if detailed studies of American mastodons’ thermoregulatory capabilities reveal that naked skin is more likely, the model could still reasonably function as a naked mastodon, albeit one with light brown skin, an artistic choice that makes it easily distinguishable from our Columbian mammoth model ( Figure 17 ).

We note that Dooley et al. ( Dooley et al., 2019) recently proposed assigning all specimens of Mammut found at La Brea Tar Pits to a newly erected species, Mammut pacificus . If this designation holds, it is unlikely to change our reconstruction. Of the morphological differences proposed between M. americanum and M. pacificus , only the lack of mandibular tusks in M. pacificus would be discernable in a model like ours ( Dooley et al., 2019). As our model lacks mandibular tusks, it should function well as either M. pacificus or M. americanum , given that not all M. americanum individuals possessed mandibular tusks.

Behavior. We used modern Asian elephants ( Elephas maximus ) for animation references given their similar size to mastodons. Group size in mast-

DAVIS ET AL.: LA BREA TAR PITS PALEOART odons is controversial. The perceived overabundance of solitary American mastodon finds compared to the large number of Columbian mammoth “crowd” finds may not represent actual behavioral differences between the two species but rather taphonomic and publication biases based on mastodons’ mixed and closed habitat preferences (Haynes and Klimowicz, 2003). We conservatively only show solitary mastodons as even if they lived in herds, one would still expect to see solitary mastodons wandering around just like with extant forest dwelling elephants.

Figures

FIGURE 2. A. Mural of La Brea Tar Pits painted by Charles Knight in 1925. B. Mural of La Brea Tar Pits painted by Mark Hallett in 1988 ©Mark Hallett. The Hallett image is not published under the terms of the CC-BY license of this article. For permission to reuse, please contact Mark Hallett.

FIGURE 17. Low poly reconstruction of the extinct Columbian mammoth (Mammuthus columbi). To view this model in 3D, please see the online version of this article.

FIGURE 18. Low poly reconstruction of the extinct American mastodon (Mammut americanum). To view this model in 3D, please see the online version of this article.

FIGURE 19. Photogrammetry model of a life sized sculpture of the extinct American mastodon (Mammut america- num) located at La Brea Tar Pits. To view this model in 3D, please see the online version of this article.